For some considerable time, thoughts have already turned to how to improve the safety of emergency vehicles in emergency service. The highway code awards special rights to emergency vehicles which indicate emergency service by means of a blue light and a horn, said special rights being intended to allow said emergency vehicles to reach their destination faster than other, civil vehicles. However, the special rights recurrently produce hazard situations, particularly when the horn and/or the blue light are/is not noticed by the other road users or only noticed late. In this case, junctions with traffic lights are particularly at risk when the emergency vehicles in emergency service enter the junction area on “red”.
To be able to better warn the other road users, DE 200 07 251 U1, which is incorporated by reference, proposes an arrangement having a vehicle-mounted transmitter which emits an electromagnetic radio signal or an infrared signal which is received by a receiver installed at a set of traffic lights. A frequency or phase comparison method can be used to infer from the received signal whether the emergency vehicle is moving towards or away from the junction and how far away it is from the junction at the time. If particular criteria are met then the traffic lights can be switched to a warning state which indicates to the civil traffic, for example by means of a rapidly flashing red light, that an emergency vehicle is approaching. Although this increases the attention of the road users, the yield of information is comparatively small, since neither the time nor the direction from which the emergency vehicle is approaching are indicated.
DE 195 08 043 C1, which is incorporated by reference, discloses a control arrangement in which a traffic lights computer stores all approaches to a junction by capturing GPS coordinates. An emergency vehicle continually transmits its position data in the form of GPS coordinates for reception by the traffic lights computer. These are used to ascertain the trajectory of the emergency vehicle. It is thus possible to predict at what time the emergency vehicle will cross the junction, possibly even in which direction, so that one arm of the junction can be provided with exclusive privilege. However, the installation of such a system is very complex both in terms of hardware complexity and in terms of the capture of the junction coordinates in the traffic lights computer.
As an extension to this system, the thesis by M. Stein, “Erstellung einer Fahrwegfreischaltung für Einsatzfahrzeuge an Ampelkreuzungen basierend auf Fahrzeug-zu-Infrastruktur Kommunikation” [Production of roadway clearance for emergency vehicles at traffic-light junctions on the basis of vehicle-to-infrastructure communication], Darmstadt Technical University, 2007, which is incorporated by reference, discloses roadway clearance for emergency vehicles at traffic-light junctions which involves learning a digital map of the surroundings by communicating with civil road users. Following the learning process, an emergency vehicle trajectory ascertained using a direction-based algorithm is classified on the basis of said learnt map. This facilitates the setup of the roadway clearance at the installation, so that the proposed method is also suitable for mobile traffic lights, for example. The roadway clearance certainly increases road safety as a whole.
However, this does not improve orientation for the civil road users sensing the horn of an emergency vehicle. In particular, experience shows that it is a problem for the driver of a vehicle involved in the traffic to identify where the emergency vehicle is located when the horn is sensed. The result of this is that the driver is frequently unable to react to the warning in a manner appropriate to the situation.
It is therefore an object of the present invention to propose a means of improved location of an emergency vehicle by a civil road user.